It's my understanding that only elements with atomic weights up to iron can be generated through normal star fusion, and (almost?) all heavier elements were formed via supernovae. Wouldn't that suggest that we have the remnants of supernovae all around us?

Every two minutes, a picture of the Earth, the Moon, and the Sun - a 360-degree panorama of the heavens - appeared in the spacecraft window. And I’d studied astronomy, and I’d studied cosmology, and I fully understood that the molecules in my body and the molecules in my partners’ bodies and in the spacecraft had been prototyped in some ancient generation of stars - in other words, it was pretty obvious from those descriptions that we’re stardust.” - Apollo Astronaut Edgar Mitchell

It's my understanding that only elements with atomic weights up to iron can be generated through normal star fusion, and (almost?) all heavier elements were formed via supernovae. Wouldn't that suggest that we have the remnants of supernovae all around us?

If that is true do they look for areas affected by a supernova to determine possible locations of earth-like planets?

It's my understanding that only elements with atomic weights up to iron can be generated through normal star fusion, and (almost?) all heavier elements were formed via supernovae. Wouldn't that suggest that we have the remnants of supernovae all around us?

Basically, yes. Anything heavier than iron was made in a supernova, and that stuff is all around us. (Assuming that by "all around" we understand that the solar system is still 99.86% hydrogen and helium, and 99.95% H, He, C, N, O.)

It's my understanding that only elements with atomic weights up to iron can be generated through normal star fusion, and (almost?) all heavier elements were formed via supernovae. Wouldn't that suggest that we have the remnants of supernovae all around us?

If that is true do they look for areas affected by a supernova to determine possible locations of earth-like planets?

Sort of yes but not exactly because of that. Kepler is looking at stars near us along the axis of the "arm" of the Milky Way. This entire part of the galaxy has roughly similar metalicity. So yes, we're looking for Earth like planets in a part of the galaxy that has been roughly similarly "affected by supernova" as we have. But that's also because that's the most star-dense part of the galaxy that we _can_ look at. Kepler isn't looking that far away.

It's my understanding that only elements with atomic weights up to iron can be generated through normal star fusion, and (almost?) all heavier elements were formed via supernovae. Wouldn't that suggest that we have the remnants of supernovae all around us?

If that is true do they look for areas affected by a supernova to determine possible locations of earth-like planets?

This is done implicitly when requiring a candidate system to have high metallicity to be put high on the search list.

I wonder how often oxygen-16 in space will capture a neutron from cosmic radiation to form oxygen-16. If a dust cloud containing oxygen-16 can linger for eons before it completely collapses to form a solar system, what percentage of that cloud would now be oxygen-17?

I wonder how often oxygen-16 in space will capture a neutron from cosmic radiation to form oxygen-16. If a dust cloud containing oxygen-16 can linger for eons before it completely collapses to form a solar system, what percentage of that cloud would now be oxygen-17?

It's my understanding that only elements with atomic weights up to iron can be generated through normal star fusion, and (almost?) all heavier elements were formed via supernovae. Wouldn't that suggest that we have the remnants of supernovae all around us?

If that is true do they look for areas affected by a supernova to determine possible locations of earth-like planets?

By the time a planet could be formed (much less by the time it becomes "Earthlike") the star would have had to have moved out of the gas cloud it formed in (if the cloud had not completely dispersed or collapsed into other stars).

Takes millions of years for a start to form, and then longer for planets to form around it.

You guys must be as old as these stars, quoting Sagan and Mitchell, and blind as black moles too if you are not able to see that Scott Johnson is the Sagan of our times and he is the one that should be quoted. This exceptional article is one of the best writings in science popularization I have read in a long time, thanks Scott.

You guys must be as old as these stars, quoting Sagan and Mitchell, and blind as black moles too if you are not able to see that Scott Johnson is the Sagan of our times and he is the one that should be quoted. This exceptional article is one of the best writings in science popularization I have read in a long time, thanks Scott.

"Massive stars (pre-explosive supernova) are composed of concentric layers of gas, each with different elements. According to our understanding of these stars, silica should only be able to solidify in oxygen-rich layers near the core."

I thought stellar cores were a bit too warm (particularly in massive presupernovae) for molecular formation, much less solidification. As in plasmas? Am I missing something obvious (not first time)?

You guys must be as old as these stars, quoting Sagan and Mitchell, and blind as black moles too if you are not able to see that Scott Johnson is the Sagan of our times and he is the one that should be quoted. This exceptional article is one of the best writings in science popularization I have read in a long time, thanks Scott.

Scott Johnson is a perfectly good writer and may be a perfectly good scientist as well for all I know, but he's hardly Carl Sagan, who was a towering giant in the field of astronomy and astrophysics. IN ADDITION to that he was quite effective as a spokesperson for science. I'll give Scott the benefit of the doubt and say he still may have time to grow to a more illustrious stature, but he'll have to bust some serious ass to be mentioned in the same sentence with Dr Sagan.

"The nitrogen in our DNA, the calcium in our teeth, the iron in our blood, the carbon in our apple pies were made in the interiors of collapsing stars. We are made of starstuff." – Carl Sagan

Echo this sentiment, everything heavier then iron would have to have been made in another star, wouldn't it? Isn't there already a lot of stuff from dead stars on Earth?

Indeed...the difference here is that the overwhelmingly vast majority of the star-stuff around us has "reacted" in some way, shape or form. These grains give scientists the chance to study unaltered star-stuff, and develop models that accurately describe how the internals of massive stars work.

You guys must be as old as these stars, quoting Sagan and Mitchell, and blind as black moles too if you are not able to see that Scott Johnson is the Sagan of our times and he is the one that should be quoted. This exceptional article is one of the best writings in science popularization I have read in a long time, thanks Scott.

It was an especially good article. It's OK to appreciate both authors.

Want to hear my side of the story? While we laugh all we wanted at the funny little looking human-made android or robot as they are made out of a piece of junk sheet metal. I got news for you, we have forgotten we are as well this Universe android and human are actually made of something of less value.. A piece of carbon.

You guys must be as old as these stars, quoting Sagan and Mitchell, and blind as black moles too if you are not able to see that Scott Johnson is the Sagan of our times and he is the one that should be quoted. This exceptional article is one of the best writings in science popularization I have read in a long time, thanks Scott.

Scott Johnson is a perfectly good writer and may be a perfectly good scientist as well for all I know, but he's hardly Carl Sagan, who was a towering giant in the field of astronomy and astrophysics. IN ADDITION to that he was quite effective as a spokesperson for science. I'll give Scott the benefit of the doubt and say he still may have time to grow to a more illustrious stature, but he'll have to bust some serious ass to be mentioned in the same sentence with Dr Sagan.

Carl was a great spokesperson for science. He was not a "towering giant" in astronomy and astrophysics. Unless someone has changed what that normally means for a field of study.